Elbow magnifying lens

ABSTRACT

A four element magnifier with right angle prism which includes, in the direction from the eye to the object, a three-component lens with two cemented surfaces, two single collecting lens and a further two-component collecting lens with one cemented surface which is adjoined by a right angle prism.

R 3,663,092 77 uulwtl DIH Schlegel ELBOW MAGNIFYING LENS [72] Inventor:

[73] Assignee:

Franz Schlegel, Munich, Germany Optische Werke G. Rodenstock, Munich,Germany [22] Filed: July27, 1970 [21] Appl.No.: 58,632

[30] Foreign Application Priority Data July 25, 1969 Germany ..P 19 37797.0

[52] US. Cl. ..350/176, 350/202 [51] int. Cl i. G02b 1/00, G02b 17/00[58] Field of Search ..350/176, 202

[15] 3,663,092 2 [45] May 16,1972

[56] References Cited FORElGN PATENTS OR APPLICATIONS l 145,822 3/1963Germany ..350/202 427,341 6/1967 Switzerland ...350/202 441,806 1/1968Switzerland .350/176 Primary Examiner-David Schonberg AssistantExaminer-Paul A. Sacher Att0rneyCraig, Antonelli & Hill [5 7] ABSTRACT Afour element magnifier with right angle prism which includes, in thedirection from the eye to the object. a threecomponent lens with twocemented surfaces, two single collecting lens and a furthertwo-component collecting lens with one cemented surface which isadjoined by a right angle prism.

5 Claims, 1 Drawing Figure PATENTEDHAY 16 I972 3 663 O92 d5. Y [L Vl/7714271 5 will/ WM [5 INJENTORI FRANZ SCHLEGEL BY: cmaflm,

M will RTTOKNEYS The present invention relates to a magnifier for theobservation of a plane or flat object surface, for example, of theluminescent screen or target of an image converter tube whereby the pathof rays between this object surface and the lenses of the magnifier arebent at a right angle through a prism. Such types of magnifying lensesare to possess an enlargement or magnification factor of to times, i.e.,have a focal distance between 16 and mm, preferably a focal distance ofabout 20 mm, and a field angle of at least 50. Since an eye more or lessadapted to darkness has to oberve the screen or target with a largepupil through the magnifying lens, a high aperture ratio results, forwhich the magnifying lens has to be corrected for the customary imagedefects and abberations. The space between the object surface andmagnifier, i.e., the distance between back lens and object, is filledwith a very highly refractive glass in order to be able to accommodatein that case a right angle prism with shortest possible optical glasspath.

Such a type of magnifier is already known as such in German Pat. No.1,260,190.

However, it has been found that with the improvement of the luminescentscreens or targets in image converter tubes, also the image power of themagnifier optics has to be increased; it is necessary for that purposeto distribute the refractive powers more uniformly over the individualimageforming elements of the angular magnifying lens which altogetherincludes four elements each with collective or condenser effect. Twoinner single collective lenses are enclosed by cemented lens elements,of which the cemented lens element facing the prism or object surfaceincludes a single cemented surface whereas the cemented lens elementfacing the eye includes two cemented surfaces. It is obvious that thetube wall of the image converter is included in the correction, andthat, apart from this tube wall, glasses are utilized throughout whoserefractive index lies only occasionally below the value of L7 while therefractive index for several lenses of the system amounts to about 1.8and above.

Accordingly, it is an object of the present invention to provide amagnifier which avoids by simple means the aforementioned shortcomingsand drawbacks encountered in the prior art.

Another object of the present invention resides in an improved elbowmagnifier which permits the attainment of an increase in the opticalpower thereof.

A further object of the present invention resides in an improved angularmagnifying lens which achieves the aforementioned aims and objects bysimple means utilizing only four lens elements and a prism.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

The single FIGURE is a somewhat schematic, axial longitudinalcross-sectional view through a magnifying lens in accordance with thepresent invention and illustrating the various optical elements thereofaccording to the Example I! of the following Table 2.

Referring now to the single FIGURE of the drawing, the magnifying lensin accordance with the present invention includes four lens elementsgenerally designated by reference numerals 10, 20, and 40. The lens unit10 which is located nearest the eye of the viewer, consists of threelens components 10', 10" and 10" joined along two cemented surfaces, ofwhich the lens element 10' is a converging meniscus, the lens element10" a diverging meniscus or a plano-concave lens and the element 10" aconverging meniscus or a planoconvex lens. The two inner lenses 20 and30 are single lenses and form a converging meniscus or plano-convex lens(lens 20) and a biconvex lens (lens 30). The lens unit consists of twocomponents 40 and 40 with a single cemented surface therebetween, ofwhich the lens 40' is a biconvex lens and the lens 40" a plano-concavelens. Reference numeral designates a right angle prism by means of whichthe light rays are deflected through 90. lnterrnediate the object,formed,

5 for example, by the target of an image converter tube, is a glasselement generally designated by reference numeral which is the anodedisc. The space between anode disc and magnifier is filled with a veryhighly refractive glass in order to be able to utilize a right angleprism with an optical glass path 10 that is as short as possible.

As to the rest, the task to achieve an increased image output, ascompared to the aforementioned prior art, by a more unifonn distributionof the powers of refraction, is assured by an optical system having thedata and surface powers of refraction that lie within the rangesindicated in the following Table 1. This Table l is valid for about f=l.

in the following Table 2 are indicated two examples with a focaldistance of about f l9 mm.

o Analogous units are used in Tables l and 2 for the various parametersin which s, is the distance between the fluorescent coating and the tubewall, i.e., the fluorescent coating is directly applied to the tubewall, in which coating the picture to be observed is produced. r with anappropriate suffix refers 25 to the respective radius of curvature, dwith an appropriate suffix to the respective thickness of a givenoptical element along its axial dimension, 1 with an appropriate suffixto the axial spacing between the surfaces of two adjacent opticalelements and da with an appropriate suffix to the power of refrac- 30tion of a surface, thus d =(n'-n) r, where n and n are the refractioncoefiicient in front of and behind the surface in question and r is theradius of curvature of the surface.

d1=6.1 1. 510/61 11=s.1 1. 510/61 rzw r2= m d==34 1. 7B9/43.6 12=34 1.789/4311 nm r1= w d =1 3 1. 840/410 d =1.25 1. 928/2L3 n=+80.3 r.=+58.7

d1=10.5 1. 694/54. 5 d.=1o.3 1. 694/54. 5

roman 04's.

TABLE 2 Continued While I have shown and described only one embodimentin accordance with the present invention, it is understood that the sameis not limited thereto but is susceptible of numerous changes andmodifications as known to those skilled in the art, and I therefore donot wish to be limited to the details shown and described herein, butintend to cover all such changes and modifications as are encompassed bythe scope of the appended claims.

lclaim:

l. A magnifying lens, with a field angle of at least about 50, and withan object space substantially filled with a glass, essentiallyconsisting of four collecting lenses. of which the two inner lensesrepresent single lenses and the two outer lenses cemented lenses,characterized by the following data;

ne/ e (1s=5.95 l. 721/47. 7 n: -l03.3

cl.-= 10.0 1. 855/23. 6 m= da=3.5 1. Still/20.2 ru=+ wherein r, refersto the respective radius of curvature, d,,

refers to the respective thickness of a given optical element along itsaxial dimension, l,,is the axial spacing between the surfaces of twoadjacent optical elements, n refers to the index of refraction, and y isthe Abbe number.

2. A magnifier, with a field angle of at least about 50 and with anobject space substantially filled with glass, that ineludes fourcollecting lens elements of which the two inner elements are singlelenses and the two outer elements are cemented lenses, characterized bythe following relation:

l lie/ s l-z=0.05-0.15 5 rs= d;=0.050.08 wa=-0.030.09

(11=0.5O.6 ip:=+0.3-+

15=0.3O.4 qoo=+O.1 +0.18

F0002 Pl0=+ -3-+ dr=0.20.6 w13=-0.03+0.12

d5=0.150.6 wu=-O.l5-0.35

wherein r, refers to the respective radius of curvature, :1. refers tothe respective thickness of a given optical element along its axialdimension, 1,, IS the axial spacing between the surfaces of two ad acentoptical elements It refers to the index to the refraction, y is the Abbenumber and =(n-n)/r, the power of refraction of a surface. 3. Amagnifier accordingto claim 2, characterized by the following data:

lie/ a d1=5.1 1. 510/61 r2= m d =1.3 1. 840/12. 0 ru=+80.3

dd 10.5 1. 694/54. 5 n=43.6

tle=5.7 1. 721/47. 7 rn=+141.8

ls=0.1 f :=+31.06

d;=4.s 1.721/477 m=+52.9

wherein r, refers to the respective radius of curvature, d, refers tothe respective thickness of a given optical element along its axialdimension, 1,,1s the axial spacing between the surfaces of two ad acentoptical elements, n

refers to the index of refraction, and 7 is the Abbe number. 4. Amagnifier according to claim 2, characterized by the following data:

ugly,

di=5.1 1. 510/61 r2: Q

l1=0.5 n: on

l2=1.7 Is: a) d =1.25. 1. 928/2L3 wherein r,, refers to the respectiveradius of curvature, d

refers to the respective thickness of a given optical element along itsaxial dimension, 1,,is the axial spacing between the surfaces of twoadjacent optical elements, n refers to the index of refraction, and 7 isthe Abbe number.

5. A magnifying lens with a field angle of at least about 50", and withan object space substantially filled with a glass, essentiallyconsisting of four collecting lenses, of which the two inner lensesrepresent single lenses and the two outer lenses cemented lenses,characterized by the following data;

lnnvn. a

1. A magnifying lens, with a field angle of at least about 50*, and withan object space substantially filled with a glass, essentiallyconsisting of four collecting lenses, of which the two inner lensesrepresent single lenses and the two outer lenses cemented lenses,characterized by the following data;
 2. A magnifier, with a field angleof at least about 50* and with an object space substantially filled withglass, that includes four collecting lens elements of which the twoinner elements are single lenses and the two outer elements are cementedlenses, characterized by the following relation:
 3. A magnifieraccording to claim 2, characterized by the following data:
 4. Amagnifier according to claim 2, characterized by the following data: 5.A magnifying lens with a field angle of at least about 50*, and with anobject space substantially filled with a glass, essentially consistingof four collecting lenses, of which the two inner lenses representsingle lenses and the two outer lenses cemented lenses, characterized bythe following data;